JP3421389B2 - Packet line backup method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet line backup system for backing up a terminal line in a packet switching system by a circuit switching network.

[0002]

2. Description of the Related Art Conventionally, a packet switching system that employs a method of backing up a circuit of a packet line by a circuit switching network has a terminal accommodating circuit that accommodates a data terminal through a terminal circuit and a circuit switching network for the data terminal. And a trunk to be accommodated via a through subscriber line. For example, when the data terminal A connected to the packet switching system A and the data terminal B connected to the packet switching system B carry out permanent fixed connection service (PVC) communication, no failure occurs in the packet transfer route. Normally, in the switching system A, the terminal line connection from the data terminal A to the packet terminal accommodation circuit and the terminal line connection from the time division switch to the packet protocol processing device are set.
If the terminal line fails at this time, a backup connection from the data terminal A through the circuit switching network to the trunk and from the time division switch to the packet protocol processor is set. The packet protocol processing device normally transmits and receives packets to and from the data terminal A through the terminal line connection. For example, the packet from the data terminal A is transferred to the trunk line trunk via the packet switch, and is transferred from the trunk line trunk to the trunk line trunk of the switching system B through the trunk line. In the switching system B, a route from the data terminal B to the packet terminal accommodation circuit and a route from the time division switch to the trunk trunk is set, and the packet communication between the data terminal A and the data terminal B is performed by this route.

The central control unit provided in this switching system A controls each device in the system, controls the setting and release of the terminal line connection in the normal state and the backup connection in the case of a terminal line failure, and also performs the line switching. Request a terminal connection to the network.

The packet protocol processing device provided in the switching system A has a layer 2 control section, an intra-network transmission control section, and a layer 3 processing section. The layer 2 control section is a normal terminal with the data terminal A. Packets are transmitted / received to / from the data terminal A via the line connection and the backup connection in case of a terminal line failure, the link level of layer 2 is controlled, the state change is notified to the central control unit from the signal control bus, and the received packet is layered. 3 Send to processing unit. The intra-network transmission control unit transmits / receives the packet to / from the packet network through the trunk trunk, and sends the received packet to the layer 3 processing unit.

The layer 3 processing section has a packet analysis section for processing a received packet, a layer 3 state transition processing section, and a packet transmission control section. The packet analysis unit extracts the packet header from the received packet and analyzes the packet type, format, and additional service element. The layer 3 state transition unit determines a transmission packet in response to the current state, the reception packet, and the terminal information set by the central control unit via the signal control bus, and transits to the next state. The packet transmission control unit passes the transmission packet to the layer 2 control unit or the intra-network transmission control unit according to the destination of the packet, and controls the packet transmission to the data terminal and the trunk trunk from these.

When the packet protocol processing unit of the switching system A detects a data link failure of the terminal line while the data terminal A and the data terminal B are communicating packets through the switching systems A and B, the reset packet is transferred to the trunk line trunk. Via the data terminal B of the switching system B via the signaling control bus to the central control unit. Next, the central control unit of the switching system A releases the terminal line connection connecting the packet terminal accommodating circuit and the packet protocol processing unit, and makes a connection request from the trunk A to the data terminal A via the circuit switching network, When receiving the connection response from terminal A,
A backup connection is set up from the data terminal A to the circuit switching network, the trunk A, and the time division switch to the packet protocol processing device. When the backup connection is set, the packet protocol processing device sends a call setup restart packet to the data terminal A according to an instruction from the central control unit, and the system B is sent from the trunk line trunk.
A reset packet is transmitted to the data terminal B, and the reconnection with the data terminal A is notified. In this way, in the conventional packet switching system, the packet communication is performed by the backup line.

[0007]

However, in the conventional packet line backup system, when the packet protocol processing device detects a data link failure with the data terminal in the terminal line connection, the terminal line connection is released and the backup line connection is established. However, since the packet protocol processing device is switched to, there is a problem that the recovery of the data link failure in the terminal line connection cannot be detected. Furthermore, if the packet protocol processing device itself fails, the backup line connection cannot be set, which causes a problem that communication between data terminals is disabled. In this case, PV that is specifically for immediate communication
If the C communication is cut off, there is a problem in that a system composed of data terminals and the like will cause a serious failure and damage.

The present invention solves the above-mentioned drawbacks of the prior art, can monitor the fault condition and recovery of the terminal line, and can also perform packet communication by the backup line even when the packet protocol processing device itself fails. It is an object to provide a packet line backup method that can be performed.

[0009]

In order to solve the above-mentioned problems, the packet line backup system of the present invention uses a first line via a backup line composed of a terminal line to which packets are transferred and a line switching network. Packet exchange with the second terminal device connected to the other party's packet switching system, and when the terminal line fails, the packet with the second terminal device is sent via the backup line. In a packet line backup method in a packet switching system for exchanging data, first packet protocol processing means for controlling a packet procedure with a first terminal device via a terminal line, and a first terminal via a backup line. Second packet protocol processing means for controlling packet procedures with the device, and first and second packet protocol A connection means for connecting any one of the packet protocol processing means of the processing means to the packet switching system of the other party, and a first and a second packet protocol processing means and a connecting means are controlled, and between the first and second terminal devices. Control means for controlling the packet transfer of the first protocol processing means, the first protocol processing means includes a failure monitoring means for monitoring a data link failure in the terminal line, and notifying the control means of the monitoring result, and the control means includes the failure. It is characterized by further comprising setting means for making a setting for selecting either the terminal line or the backup line according to the monitoring result from the monitoring means.

In this case, the packet communication in the terminal line connection and the backup line connection is preferably PVC communication for fixedly connecting the terminals.

In addition, the packet switching system indicates that the other packet switching system accommodating the terminal device of the communication partner of the own terminal device is changed from the first packet protocol processing means to the second packet protocol processing means.
The change notification packet including the communication information may be transmitted, and the other packet switching system may update the PVC communication information based on the change notification packet.

[0012]

According to the present invention, the first line corresponding to each of the terminal line connection and the backup line connection is provided.
Also, by providing a second packet protocol processing device, that is, duplicating these devices with respect to the data terminal, and adding a monitoring function for monitoring the terminal line to the packet protocol processing device, communication due to a failure of the packet protocol processing device is performed. It is possible to detect the failure state and the failure recovery of the terminal line during communication on the backup line. Also, the PVC can be changed and set by notifying the packet switching system of the communication path of the change of the packet protocol processing device at the time of backup.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A packet line backup system according to the present invention will be described below with reference to the accompanying drawings. Referring to FIG. 1, there is shown an embodiment of a packet switching system to which the packet line backup method of the present invention is applied. This packet switching system 10 accommodates, for example, a plurality of data terminals via a terminal line, and, between the data terminals connected to another switching system 19, a PVC (fixed connection between the data terminals). Permanent Virtual Circuit) A system that provides communication and transfers data transmission and reception as packets. It should be noted that in the description of the embodiments, the illustration and description of parts that are not directly related to the present invention are omitted.

The packet switching system (PS) 10 shown in FIG.
Is connected to a plurality of data terminals (TE) 11 via terminal lines 12, respectively, and data terminals 11 are connected via backup lines 16 passing through subscriber lines 14 and 15 of a circuit switching network 13 and further packet The switching system 10 is connected via a trunk line 20 to a packet switching system (PS) 19 to which a plurality of data terminals 18 are connected. Packet switching system 10
Sets a terminal line connection 25 that connects a terminal accommodation circuit 21 that accommodates the terminal line 12 and a packet protocol processing device (PHM) 23 via a time division switch 24. Also, the packet switching system 10 uses this terminal line connection.
When the 25 communication paths cannot be used due to a failure of the terminal line 12 and the packet protocol processing unit 23, the trunk 27 connected to the backup line 16 and the packet protocol processing unit (PHM) 28 are connected via the time division switch 24. Set the backup connection 29 to be used. These terminal line connection 25 and backup line connection
By 29, the communication path of the data terminal 11 is duplicated.

The packet switch (PKS) 30 is a packet switch for transferring packets between the packet protocol processors 23 and 28 and the trunk trunk 31 connected to the trunk circuit 20, and the packet protocol processors 23 and 28. And the trunk 31 of the trunk line. The trunk line trunk 31 accommodates the trunk line 20 connecting the switching system 10 and the switching system 19, and processes an interface with the packet communication network connected by the trunk line 20. In addition, the terminal accommodation circuit connected to the time division switch 24
21 and trunk 27 handle interfaces with terminal line 12 and circuit switching network 13, respectively.

Packet protocol processing devices 23 and 28
Controls a packet transfer procedure for transferring a packet via the terminal line 12 and the backup line 16, respectively, and a packet from the data terminal 11 transferred via the time division switch 24 is transferred to the trunk line trunk via the packet switch 30.
The packet transferred to the relay terminal 20 via the packet switch 30 is transferred to the data terminal 11 via the time division switch 24.

The central control unit 33 is connected to each of the above-mentioned units via the signal control bus 34, controls to set and release the terminal line connection 25 and the backup line connection 29, and the backup line passing through the line switching network 13. Control to set 16 and control to set PVC between data terminals. Further, the central control unit 33 receives the fault notification indicating the fault state in the terminal line 12 from the packet protocol processing unit 23, and performs control such as changing the terminal line connection 25 to the backup line connection 29. Further, the central control unit 33 includes a packet protocol processing unit 23.
It has the function of detecting the failure that occurred in the.

On the other hand, the packet switching system 19 connected to the switching system 10 via the trunk line 20 includes a data terminal (T
E) A terminal accommodating circuit 40 accommodating 18; a trunk trunk 41 connected to the trunk line 20; a packet switch (PKS) for performing packet exchange between the terminal accommodating circuit 40 having a packet protocol processing function and the trunk trunk 41. ) 42 and. Further, the switching system 19 includes a central control device 43 for controlling the terminal accommodating circuit 40, the trunk trunk 41 and the packet switch 42, respectively, and the central control device 43 uses a signal control bus 44 connecting these devices to control these devices. To control. Further, when the central control device 43 receives a change notification to the backup line connection 29 from the packet switching system 10, the central control device 43 returns the response and sets the PVC.

Next, the packet protocol processing device 23 and
The structure of 28 is shown in FIG. Packet protocol processor 23
And 28 are a layer 2 control unit 50 and a layer 3 processing unit 52.
And a terminal line monitoring unit 53 and an intra-network transmission control unit 54. Specifically, the layer 2 control unit 50 uses the terminal line port 51
It is a circuit that is connected to the time division switch 24 shown in FIG. 1 via the terminal and transmits / receives packets to / from the data terminal 11 via the terminal line connection 25 or the backup line connection 29. The layer 2 control unit 50 controls the link level of the layer 2, notifies the central control device 33 connected via the signal control bus 34 of the state change, and sends the received packet to the layer 3 processing unit 52. The terminal line monitoring unit 53 connected to the layer 2 control unit 50 is connected to the central control unit 33 by the signal control bus 34, and when receiving a terminal line monitoring instruction from the central control unit 33, the terminal line monitoring unit 53 is fixed to the layer 2 control unit 50. It requests transmission of a monitoring frame at regular intervals and monitors the terminal line 11 for failure recovery. The intra-network transmission control unit 54 is connected to the packet switch 42 via the trunk line port 55, transmits and receives packets to and from the packet network via the trunk line trunk 31, and sends the received packet to the layer 3 processing unit 52. send.

The layer 3 processing section 52 includes a packet analysis section 56 for processing a received packet and a layer 3 state transition processing section 57.
And a packet transmission control unit 58. Specifically, the packet analysis unit 56 extracts a packet header from the received packet sent from the layer 2 control unit 50, and analyzes the packet type, format, and additional service element of this received packet. The layer 3 state transition unit 57 decides a transmission packet in accordance with the current state, the received packet, and the terminal information set by the central control unit 33 via the signal control bus 34, and determines the next state. Transition. The packet transmission controller 58 is
The transmission packet is passed to the layer 2 control unit 50 or the intra-network transmission control unit 54 according to the destination of the packet, and the packet transmission to the data terminal 11 and the packet network is controlled by these.

Next, referring to FIG. 3, there is shown a flow chart of the line backup processing of the packet switching systems 10 and 19. At the normal time during packet exchange by the terminal line connection 25 set between the terminal accommodation circuit 21 and the packet protocol processing device 23, the terminal line 12
When the data link failure in (1) is detected by the packet protocol processing device 23, the central control device 33 instructs the packet protocol processing device (PHM) 23 to delete the terminal information and monitor the terminal line (S100). Next, the packet protocol processing device 28 requests a connection to the circuit switching network 13 (S101) and sets a backup line (S102). When the backup line connection is set, the central control unit 33 notifies the packet switching system (PS) 19 of the PVC communication partner of the change of the packet protocol processing unit 23 (S103). The packet switching system 19 receives the PHM change notification and sends it to the switching system 10.
Send a PHM change response (S104), and send PHM to own exchange system 19.
The PVC information with the changed information is set (S105), and the switching system
19, the backup process ends. Hand exchange system
10 receives the PHM change notification response from switching system 19.
(S106), corresponding information is set in the packet protocol processing device 28 (S107). If switching system 10 is setting up PVCs through multiple switching systems (PS), then step if the response from all switching systems is not complete.
Returning to (S106), when completed, the backup process is completed. When the failure of the packet protocol processing device 23 is detected and the terminal line cannot be monitored in step 100, the central control device 33 deletes the terminal information to the packet protocol processing device 23 and deletes the terminal information. The line monitoring instruction may be omitted. In this case, the central control device 33 may notify the switching system 19 of the failure on behalf of the packet protocol processing device 23, and recognize the response from the switching system 19.

FIG. 4 shows the backup processing sequence of this embodiment. In the packet switching systems 10 and 19, when the data link failure of the terminal line 12 to which the data terminal 11 is connected is detected by the packet protocol processing device 23, the packet protocol processing device 23 causes the signal control bus 34
A failure is notified to the central control unit 33 via the relay line and a reset packet (RI) indicating a failure condition is transmitted to the trunk 31. The reset packet (RI) is transmitted to the switching system 19 and the terminal accommodating circuit. From 40 to the data terminal 18. Upon receiving this failure notification, the central control device 33 instructs the packet protocol processing device 23 to delete the terminal information of the data terminal 11 and monitor the terminal line 12 via the signal control bus 34, and the packet protocol processing device 23, A monitoring frame of a constant cycle is transmitted to the terminal line 12 to which the data terminal 11 is connected via the terminal line connection 25, and the recovery of the fault in the terminal line 12 is monitored.

When the central control unit 33 requests the connection to the circuit switching network 13 via the trunk 27 and receives the connection response from the data terminal 11, the central control unit 33 backs up from the data terminal 11 to the trunk 27. The line 16 is set, and the backup line connection 29 from the trunk 27 to the packet protocol processing device 28 via the time division switch 24 is set.

Next, the central control unit 33 informs the central control unit 43 of the packet switching system 19 of the trunk trunk 31 and
PVC between data terminal 11 and data terminal 18 via 41
The packet protocol processor (PHM) 23, which processes packets and procedures for communication, sends to the packet protocol processor 28 the PHM change notification shown in FIG. Upon receiving the PHM change notification, the central control unit 43 sends the PHM shown in FIG. 6 to the central control unit 33 via the trunk trunk 41.
A change response is sent, and the terminal accommodation circuit 40 is instructed by the PVC setting request to change the position information of the packet protocol processing device (PHM) of the PVC communication partner.

Upon receiving the PHM change response, the central controller 33 instructs the packet protocol processor 28 to make a PVC setting request. Upon receiving the PVC setting request from the central control unit 33, the packet protocol processing unit 28 sends a restart packet (SI) to the data terminal 11 and also sends a reset packet to the data terminal 18 via the trunks 31 and 41. (RI) is sent to notify that the backup line and the backup line connection to the data terminal 11 have been opened. The packet protocol processing device 28 receives data from the data terminal 11 (S
F), receiving each response of (RF) from the data terminal 18,
The packet communication is restarted on the backup line 16.

When the packet protocol processor 23 detects the restoration of the terminal circuit 12 during the packet communication on the backup circuit 16, the packet protocol processor 28 is switched to the packet protocol processor 28.
The backup line 16 is restored to the terminal line 12.

As described above, in the packet line backup method according to the embodiment, when a failure occurs in the terminal line 12, the backup packet protocol processing device 28 can perform the line backup. In the packet protocol processing device 23 in charge of
The failure recovery of the terminal line 12 can be monitored every predetermined period. As a result, according to this method, communication can be performed on the backup line while monitoring recovery of the terminal line, and backup communication can be performed even when a failure occurs in the packet protocol processing device 23 itself.

[0028]

As described above, according to the present invention, the terminal line,
Or even if the packet protocol processor fails,
Since packet communication can be continued on the backup line, interruption of packet communication such as PVC communication is minimized. Further, during backup communication on the backup line, the first packet pro-protocol processing means monitors the failure state and recovery of the terminal line, so labor saving of the failure test and early detection of recovery of the terminal line are possible. There is an effect such as being able to.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a packet switching system to which a packet line backup method according to the present invention is applied.

FIG. 2 is a block diagram showing a configuration of a packet protocol processing device in the embodiment shown in FIG.

FIG. 3 is a flow chart of a line backup process in this embodiment.

FIG. 4 is a sequence diagram of a line backup process in this embodiment.

FIG. 5 is a diagram of a packet format of a PHM change notification in this embodiment.

FIG. 6 is a diagram of a packet format of a PHM change response in this embodiment.

FIG. 7 is a diagram of a packet format of a PVC setting request in this embodiment.

[Explanation of symbols]

10,19 Packet switching system 11,18 Data terminal 12 terminal line 13 Circuit switching network 14,15 subscriber line 16 backup line 20 trunk lines 21,40 Terminal accommodation circuit 23,28 Packet protocol processor 24,42 time division switch 25 terminal line connection 27 trunk 29 Backup connection 30 packet switch 31,41 Trunk trunk 33,43 Central control unit

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04L 12/56 100

Claims (3)

(57) [Claims] 1. A first line via a backup line composed of a terminal line to which packets are transferred and a line switching network.
The second terminal device is connected to the second terminal device connected to the other party's packet switching system, and the second terminal device is connected via the backup line when the terminal line fails. In a packet line backup method in a packet switching system for exchanging packets with a first packet protocol processing means for controlling a packet procedure with the first terminal device via the terminal line, and the backup line. Second packet protocol processing means for controlling a packet procedure with the first terminal device via the second packet protocol processing means and one of the first and second packet protocol processing means Connection means for connecting to a packet switching system, and the first and second packet protocol processes Means and the connection means, and control means for controlling packet transfer between the first and second terminal devices, wherein the first protocol processing means monitors a data link failure in the terminal line. A failure monitoring means for notifying the control means of the monitoring result, wherein the control means makes a setting for selecting either the terminal line or the backup line according to the monitoring result from the failure monitoring means. A packet line backup system comprising a setting means. 2. The packet line backup method according to claim 1, wherein the packet communication in the terminal line connection and the backup line connection is PVC communication for fixedly connecting terminals. method. 3. The packet line backup method according to claim 2, wherein the packet switching system includes a second packet switching system that accommodates a terminal device of a communication partner of the own terminal device from the first packet protocol processing means. The second packet switching system transmits a change notification packet including PVC communication information indicating the change, and the other packet switching system updates the PVC communication information based on the change notification packet. Backup method.